Equivalent circuit model of cycloconverter-fed multiphase synchronous motor system

This paper proposes a new analysis approach for analytic study of the cycloconverter-fed multiphase synchronous motor, based on the analysis of its operation characteristics. That is, the d- and q-axis variables of multiphase synchronous motor are decomposed to low-frequency components (including a periodic component) and high-frequency components, which can be treated separately. In this case, the resistance of rotor circuits to high-frequency components and the effect of damper winding on low-frequency components are negligible. And the equivalent circuit model of cycloconverter-fed multiphase synchronous motor system for steady-state and quasi-steady-state analysis is established. In this equivalent circuit model, the cycloconverter-fed multiphase synchronous motor can be seen as two parts. One is external impedance, the other is the equivalent multiphase synchronous motor whose n Y-connected 3-phase windings has no coupling and operates independently with each other. The simulation results show that this equivalent circuit model is correct for steady-state and quasi-steady-state analysis.